Initial version.

.gitignore

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+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+.*.swp
+doc/.build
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+
+TODO

README.rst

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+Flicker Noise Formulations in Compact Models
+============================================
+
+Includes a resistor model that demonstrates how to properly model flicker noise 
+in Verilog-A as described in "Flicker Noise Formulations in Compact Models", to 
+be published in Transactions on Computer-Aided Design of Integrated Circuits and
+Systems some time in 2020.
+
+Also included are two circuits. The first is a simple test circuit for the 
+resistor model. The second is a circuit that tests the implementation of flicker 
+noise in the built-in BSIM4 model.
+
+If you have a recent version of Spectre, you can simulate the circuits directly 
+and view the results in your favorite waveform viewer.
+
+If you have Python 3.6 or later, you can also run the simulation scripts, which
+re-generate the netlists, run the simulation (in Spectre), and plot the results.
+
+To install the script dependencies, from the directory that contains setup.py,
+run::
+
+   pip3 install --user .
+
+This installs all dependencies into ~/.local/lib.  Then simply run::
+
+   ./runPnoise
+
+or::
+
+   ./runBSIM
+
+These run a simulation and plot the results. You have the -v option and the 
+logfile (.runPnoise.log or .runBSIM.log) to help you out if you run into any 
+problems.
+
+You can also run a simulation of the broken resistor model::
+
+  ./runPnoise --broken
+
+You can view the signal and waveforms with::
+
+   > list-psf -f pnoise.raw/pnoise.pnoise -l
+   > plot-psf out
+
+My rather old version of Spectre (15.1.0) generated the following results:
+
+Resistor:
+
+    .. image:: results/resistor.svg
+
+BSIM:
+
+    .. image:: results/bsim.svg

broken.va

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+//  Resistor model with both thermal and flicker noise
+//
+//  This model demonstrates the wrong way to model flicker noise. It gives
+//  correct results in noise analyses but the wrong results in pnoise analyses.
+//  The issue is described in "Flicker Noise Formulations in Compact Models", to
+//  be published in Transactions on Computer-Aided Design of Integrated Circuits
+//  and Systems some time in 2020.
+//
+//  DO NOT USE THIS MODEL.
+//
+//  It is provided only to demonstrate the wrong way to write a flicker noise
+//  model.
+
+`include "disciplines.vams"
+`include "constants.vams"
+
+module res_va(a,b);
+  inout      a, b;
+  electrical a, b;
+  parameter real R  = 100.0    from (0.0:inf);
+  parameter real KF =   1.0e-6 from [0.0:inf);
+  parameter real AF =   2.0    from (0.1:inf);
+  parameter real EF =   1.0    from (-inf:inf);
+
+  analog begin : vaResistor
+    real Ir, Pn;
+    Ir      = V(a,b)/R;
+    Pn      = KF*pow(abs(Ir), AF);
+    I(a,b) <+ Ir;
+    I(a,b) <+ white_noise(4.0*`P_K*$temperature/R, "thermal");
+    I(a,b) <+ flicker_noise(Pn, EF, "flicker");
+  end
+endmodule

clean

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+#!/bin/sh
+
+rm -rf {pnoise,pnbsim}.{ahdlSimDB,raw,log}
+rm -rf .{runPnoise,runBSIM}.log
+rm -rf .*.Linux-64.dep *.ahdlcmi
+rm -rf build dist flicker_noise.egg-info

pnbsim.scs

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+// BSIM flicker noise simulations
+
+simulator lang=spectre
+
+model nchbsim4_f0 bsim4      fnoimod=0 kf=1e-23 af=2
+model nchbsim4_f1 bsim4      fnoimod=1
+
+VX (x 0) vsource type=sine dc=1.0 sinedc=0.0 ampl=100mV freq=131.072kHz
+ED (d 0 x 0) vcvs gain=1
+ES (s 0 x 0) vcvs gain=-1
+VG (g 0) vsource dc=3
+VB (b 0) vsource dc=-0.2
+
+MBSIM4f0 (d_f0 g s b) nchbsim4_f0 l=1um w=10um
+MBSIM4f1 (d_f1 g s b) nchbsim4_f1 l=1um w=10um
+
+iRESf0 (d d_f0) vsource dc=0.0
+iRESf1 (d d_f1) vsource dc=0.0
+Rout (noise 0) resistor isnoisy=no r=100kOhm
+Hnoise (noise  0) pccvs coeffs=[0 1 1] probes=[iRESf0 iRESf1]
+
+noise (noise 0) noise start=4_Hz stop=4.194304MHz dec=2k
+pop pss fund=131.072kHz
+pnoise (noise 0) pnoise start=4_Hz stop=4.194304MHz dec=2k maxsideband=10

pnoise.scs

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+// Resistor flicker noise simulations
+
+simulator lang=spectre
+
+ahdl_include "resistor.va"
+
+model rref resistor kf=1.0e-6 af=2 // to match res_va
+
+Vin    (n 0) vsource type=sine dc=1.0 sinedc=0.0 ampl=100mV freq=131.072kHz
+R1     (n 0) res_va
+R2     (n 0) rref r=100.0
+
+noise  noise start=4_Hz stop=4.194304MHz dec=2k oprobe=Vin
+pss    pss fund=131.072kHz
+pnoise pnoise start=4_Hz stop=4.194304MHz dec=2k maxsideband=10 oprobe=Vin

resistor.va

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+//  Resistor model with both thermal and flicker noise
+//
+//  This model demonstrates the correct way to model flicker noise. It gives
+//  correct results in both noise and pnoise analyses as described in "Flicker
+//  Noise Formulations in Compact Models", to be published in Transactions on
+//  Computer-Aided Design of Integrated Circuits and Systems some time in 2020.
+
+`include "disciplines.vams"
+`include "constants.vams"
+
+module res_va(a,b);
+  inout      a, b;
+  electrical a, b;
+  parameter real R  = 100.0    from (0.0:inf);
+  parameter real KF =   1.0e-6 from [0.0:inf);
+  parameter real AF =   2.0    from (0.1:inf);
+  parameter real EF =   1.0    from (-inf:inf);
+
+  analog function integer sign;
+    input arg;
+    real  arg;
+    sign = arg >= 0 ? +1 : -1;
+  endfunction
+
+  analog begin : vaResistor
+    real Ir, Pn;
+    Ir      = V(a,b)/R;
+    Pn      = KF*pow(abs(Ir), AF);
+    I(a,b) <+ Ir;
+    I(a,b) <+ white_noise(4.0*`P_K*$temperature/R, "thermal");
+    I(a,b) <+ flicker_noise(sign(Ir)*Pn, EF, "flicker");
+  end
+endmodule